Seam Welding

Questions and Answers

Information for seam welding stainless steel is published by the American Welding Society in their Welding Standards.

"AWS Standard C1.1:2019 “Recommended Practices for Resistance Welding”

A seam welder has the same components as any other resistance welding machine. These components (transformer, conductors, control and electrodes) each require independent water cooling. Flow to these components should be as specified by the manufacturer. Normally the rates are 1-1.5 gallons/minute. The duty cycle of a seam welder runs higher than most other resistance welding applications making cooling imperative.

 Water Manifold

                   COOLING WATER MANIFOLD

In addition to the normal internal component water cooling, water is frequently applied in a stream (flood cooling) directly at the weld location. This externally cools the seam welding wheels and part being welded. This flow should be at 1–1.5 gallons/minute.

 A1 178a Close up of weld wheels on part with cooling

ARROWS INDICATES EXTERNAL FLOOD COOLING WATER TUBES

FOR ADDITIONAL INFORMATION REFER TO OTHER ARTICLES IN THIS BLOG:

“WHAT IS THE PROPER AMOUNT OF WATER COOLING FOR SEAM WELDING?”

“IS THE WATER USED FOR SEAM WELDING HARMFUL AFTER BEING USED FOR COOLING?”

References: RWMA- RWMA Resistance Welding Manual 4th Edition
                    AWS- AWS Standard J1.2 Guide to the Installation and Maintenance of Resistance Welding Machines

 

 

It certainly is possible but may not be practical to convert a spot welder into a seam welder. Many major components will need to be examined and potentially redesigned or changed. This would include the transformer, conductors, machine weld head, control and plant input power to name a few. This conversion will involve the potential change from a standard electrode to a seam welding wheel and a rotating weld held mechanism. This is a major machine design change. This should be addressed with a machine builder or rebuilder of used machinery. This question is beyond the scope of this discussion.

If one wants to use a spot welder to make spot welds close together. These are referred to as stitch welds.

A1 174b Roll Spot Weld

                          VARY SPOT SPACING TO MAKE
                                      A STITCH WELD

In another article in this blog the proper amount of water for seam welding was addressed:

IS THE PROPER AMOUNT OF WATER COOLING FOR SEAM WELDING?

Yes, water temperature and volume are important for the performance of seam welding. The importance of water cooling the machine components was discussed in this referenced article. This would include the conductors, transformer and the control. The amount of flow is specified by the machine builder. The weld wheels are cooled through their attachment to the water-cooled shaft. The amount of water is frequently specified as 1 – 1.5 gallons of water per minute for these components. Each frequently has its own water circuit originating from a common water manifold to insure flow to each component. These flows cool the components for the current they carry.  The temperature of this cooling water is normally city water or cooling tower temperatures which can vary from winter to summer. In extreme cooling requirements a chiller may be required. If these components do not have the proper flow or temperature water their long-term performance will be impacted.

In resistance welding whether it is spot or seam welding build up on the face of the electrode is inevitable. It is caused by the heat generated on the electrode face and the chemical/metallurgical reactions that occur there. To reduce build up the process must be designed to maintain the face below red heat as much as possible. The process must reach red heat to make a weld. To accomplish this, the process must be designed to heat up to red heat, make the weld quickly and cool down quickly. Thus the electrode seam weld wheel face is at red heat a minimal amount of time. In roll spot seam welding there is some time/space between welds. In a liquid tight seam weld there is very little time between welds. There is not much cool time.

What can be done to protect the seam weld wheel?

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